Photoperiodic-dependent morpho-biometric changes in the excurrent duct system of sexually-matured helmeted guinea fowl (Numida meleagris)

Abstract

Photoperiod is considered to be one of the most effective environmental factor in controlling the reproductive cycle and gonadal maturation in some mammalian species, but very limited information are available on its effects on reproductive biology of the guinea fowl. Therein, we investigated the effects of varying photoperiodic treatments on morpho-biometry of the excurrent duct system of helmeted guinea fowl (Numida meleagris). A total of twenty-one (21) apparently healthy sexually-matured helmeted guinea fowls were randomly assigned into three (3) photoperiodic regimes; mainly [Group I: Short daylight (SD; 8 HL (Hour of light, Group II: Moderate daylight (MD; 12 HL) and Group III: Long daylight (LD; 16 HL)] of seven birds per group (n=7). After 8 weeks of experimentation, the excurrent ducts were excised and freed of all adhering connective tissues for gross-morphological and morphometric evaluations. The bio-morphometric data (weight and diameter) were significantly increased (p< 0.05) in the epididymis and ductus deferens of guinea fowl exposed to 16 HL, as compared to other treatments. However, no significant (p> 0.05) effect was observed in body weight and length of the excurrent ducts regardless of photoperiod. The observed changes in weight and diameter of the epididymis and ductus deferens of helmeted guinea fowl are thus a consequence of the stimulatory effects of long photoperiod exposure to reproductive activity. Thus, these findings would therefore be useful to guinea fowl breeders in designing appropriate intervention programs necessary to improve their reproduction efficacy and to preserve this species.